Another 2150 jet question.

[Jimbos76cj]

Sorry to ask this again. Im going to pull the trigger on a jet change and not sure what size to drop down to. My 2150 came from waggy 360 which I hear can have jets from 53-63 in them. My Motor is a AMC 258 i6 / 4.2l with a "RV" cam, Long tube headers, and Full MSD ignition. My plugs are at .05 and timing at 10*. Jeep runs great how ever I noticed a pretty heavy gas smell from the exhaust and I have a pretty decent amount of soot in the new exhuast pipe. I pulled #1 plug and was surprised at how black it was. To me normally a plug this black is causes a really bad running motor. Im guessing the MSD ignition and wider gap are keeping it up and running. So my question is with the mods to the motor do I go straight down to a 47? I was thinking about ordering a set of 50 and 48 and seeing which one the motor likes better. Oh and my first tank netted 10mpg running 33" tires, 3:73 gears and ,79 over drive. It cruises 55 at 1500rpm.

 

[Woolyworm]

What is the number stamped on the side of that carb? 1.??


Wooly

 

[Jimbos76cj]

What is the number stamped on the side of that carb? 1.??


Wooly

Not sure.. I looked at the area where it should be stamped and its just a rasied disc with no stamping.. Id assume 1.2 since it came off a waggy and mosy seem to be 1.2

 

[Woolyworm]

Are you concerned about that much Venturi with that small of a motor? I have a 1.08 on my AMC 304 which is recommended by others and works well from my experience. Here is a calculator. http://www.csgnetwork.com/cfmcalc.html

But - to pick your jets it's really trial and error. Figure out what's in the and go down a couple of sizes then check your plugs. You can add a sensor to you exhaust with a gauge if you like.

I'm concerned that with that much air, your going to have s hard time balancing things out on that AMC 258 i6 / 4.2l .


Wooly

 

[Woolyworm]

After a little research - it's either a 1.08 with 287 CFM or a 1.21 with 351 CFM.. The 1.08 was used in 6's and small 8's, the 21 on bigger 8's.


Wooly

 

[Jimbos76cj]

Thanks wooly.. I pulled the top and found I had one 48 and one 51 jet in the carb. How do they measure the the openings? Is a 51 = to .051" the 48 and 51 look identical in diameter.. 48 May actually look bigger.

 

[Woolyworm]

Bigger number is bigger hole.


Wooly

 

[Woolyworm]

Yes on the sizing.


Wooly

 

[Woolyworm]

Someone may have drilled the 48 over.


Wooly

 

[Jimbos76cj]

I ordered a set of 47'e and 48's.. I actually ordered 2 sets of each since I didnt read the part where it said pr next to the price. Im hoping to get it back on the road saturday.. Will report back.

 

[Woolyworm]

Good luck!


Wooly

 

[Jimbos76cj]

Good luck!


Wooly

Thanks. I left the top of the carb off while I waited for the jets to arrive (about 2 weeks total) I never added a vent to my tank and in the florida heat Im assuming the tank built pressure and pushed gas back into my notor. After a installing the new jets I had a really hard time getting her started and when it finally did it ran and sounded bad for about 30secs before stalling out. When I looked under the hood every thign was covered in a oil/gas mixture. I pulled my dipstick and the motor was over filled by about 2 gallons of straight gas! I did several cycles of prime the oil pump, crank motor by hand then. Then I changed it again and cranked it with the starter. Then changed the oil and fired her up. Started right up but had a horrible knock. Sounded like right in the front either a rod or bearing. I complained to a buddy and he came over and quickly said it sounded like the balancer is hitting the timing chain cover. I could have kissed im. While I was waiting on the jets I installed the OBA which included an add on pulley for the balancer. The pulley didnt come with bolts so I grabbed a few longer ones from the bolt bin and they seemed to fit with no issue. I pulled the extra pulley and put the stock pulley bolts back in and started it back up. No noise. Engine runs good and does not seem to have any residual issues from the gas except the RMS is leaking. Im hoping all the drips were residual from the first gas start up and it will stop with hte heavier oil.. If not new RMS and pan gasket in the future.

 

[Woolyworm]

Wow! So do you think you've got the jetting right now?


Wooly

 

[Jimbos76cj]

Well it idles smooth and doesn't stink like gas when you rev the motor. Im gonna drop the tank so I dont want to refill it again until the roll over/vent and charcoal canister are all installed. Once thats all done and Im not afraid to leave the gas cap on Ill take her for a trip and check the plugs. Ill also keep up with the MPG. I figured AMC 258 i6 / 4.2l with a ax-15 on 33's with 3:73 gears would do better then 10mpg that I was getting at first.